1. Field of the Invention
The present invention relates to a laser distance measuring apparatus for calculating the distance between wall surfaces used, for example, in housing construction site or electric work site.
2. Description of the Prior Art
As distance measuring apparatus of this kind, hitherto, a dimension measuring apparatus 20 as shown in FIG. 23A is known (for example, see Japanese Laid-Open Patent Publication No. HEI 8-35820). This dimension measuring apparatus 20 comprises a cursor 22 sliding along a bar member 21, an encoder for generating a pulse at every specific moving distance of the cursor 22, photo detectors 23a, 23b for detecting the laser beam, an LCD device 24, and others. The method to use this apparatus 20 is shown in FIG. 23B, in which a laser projector 26 is installed at a reference position in a room 25, light beams are emitted in four orthogonal directions B1, B2, B3, B4, this apparatus 20 is placed in the room 25 in solid line state and broken line state, and while the cursor 22 is moved along the bar member 21, the light beam is detected by the photo detectors 23a, 23b, and the moving distance of the cursor 22 at this time is read. Thus, the dimensions of the room 25 are measured.
As other conventional distance measuring apparatus, a dimension measuring apparatus 30 as shown in FIG. 24A is known (for example, see Japanese Laid-Open Patent Publication No. HEI 5-288549). This apparatus 30 comprises a turntable 32 rotatably mounted on a base 31, a motor 35 for rotating and driving it, a rotary encoder 33 for generating pulses in the number proportional to the rotational angle of the turntable 32 on the base 31, a laser range finder 34 mounted on the turntable 32, and others. The method to use this apparatus 30 is shown in FIG. 24B, in which reflectors (not shown) are installed at reference points X, Y, Z of a room 25 to be measured, the numerical count of the counter when the laser range finder 34 of the apparatus 30 directs at angles θ2, θ3 is stored as angle data, and the output data from the laser range finder 34 is stored as distance data L1, L2, L3. Thus, the apparatus 30 is installed in the room 25, reflectors are placed at measuring points, and distance signals obtained by emitting from the laser range finder 34 to the reflectors is read out at every rotational angle θ2, θ3, and this process is repeated at every corner or specified reference point of the room 25. As a result, diagonal lengths S2, S3, and other dimensions of the room 25 can be measured.
In further different prior art, using a plurality of laser type displacement meters provided on a body of a running vehicle, the interval of laid rails is detected, the detection position is specified by an arithmetic unit, and the rail interval is evaluated (for example, see Japanese Laid-Open Patent Publication No. HEI 6-42927). In this laser type displacement meter, laser is emitted parallel to the axles at right and left gauge corners (wheel flange sides) of rails, and the distance between the rails is continuously determined from the reflected light.
In these dimension measuring apparatuses 20, 30 and rail interval measuring apparatus, however, the dimension of only one direction can be measured. That is, in order to measure the distance between two objects apart from each other, since one irradiating and measuring point of the apparatus is needed, the distance must be measured plural times by changing the apparatus installation state, using one end face of the two objects as the reference, or a reflector must be installed at the reference position, and it takes much time and labor, and it requires much experience and skill to enhance the precision of measurement. In a mechanism designed to rotate the entire apparatus, the structure is complicated and increased in size.